Student asked me what's the transformations

Brian McLogan
1.3K followers
11.2K Video Views·Jan 1, 2025
a student online sent me this video for
me to be able to identify the
Transformations so what I want to do in
this video is to help you as well as
help them with their problem so let's go
ahead and write out the problem on this
board so therefore I can kind of work
through
it all right so if I was approaching
this problem and helping the student
they're sitting right next to me a
couple things I would recognize or a
couple things I would work out with them
first we need to understand when we're
trying to identify the Transformations
we want a quadratic to be in the form y
= a * x - h^ 2 + K that is going to be
our vertex form where a remember is
going to be our stretch as well as our
compression vertical stretch and
compression also a is going to reflect
about the x-axis H is going to be your
horizontal shift left and right and K is
going to be your vertical shift up and
down the problem that we have in this
equation is this is in standard form y =
ax^2 + BX plus C so what we need to do
in this problem before we can identify
the Transformations we need to go from
this form all the way over to that form
and the process of doing that is called
completing the square now to go about
completing the square there's a couple
things we need to kind of look at first
or kind of have like a little checklist
the first thing is we cannot have a
coefficient of our quadratic term so
what we need to do is we need to be able
to get that term away from the X squ now
the way to do that is going to be a
little confusing in this problem because
a lot of times students don't think to
apply this process but I don't want to
kind of do it a different way I want to
be able to approach everything thing
we're keeping the Y on the left hand
side and we're just going to only work
here on this right hand side so to get
this -2 outside of it what I simply need
to do is I need to factor out a -2 from
the -2X 2 as well as from the 5x and
that's even more confusing because I
know I can factor a -2 from here but how
do I factor out a -2 from the five well
here's the kind of important things if
you have a five and let's say you factor
out a
-2 well then all you need to Simply do
is rewrite A5 divided by -2 and you can
see that this still equals A5 so when
I'm factoring out a-2 think about that
as like dividing out the -2 and since -2
doesn't evenly divide into five my
resulting answer is going to be 5 over
-2 so the answer or the expression is
going to look like
this all right so now what I've done is
I have now taken out this factor out
this ne-2 so now inside this parentheses
I have an x^2 minus a 5 x now I have
something I can work with for completing
the square because again the idea of
completing the square is I need to go
from standard form where I have this X
squ all the way over to now where I have
a quantity x - h^2 so what we need to do
is we need to create what we call a
perfect square trinomials because
perfect square trinomials can be
factored down into binomial squared if
you remember like a common one like x^2
+ 2x + 1 this is called a perfect square
trinomial this can be Factor down into x
+1 * an x + 1 which can be simplified
into an x +1 quantity s that is what we
need to create unfortunately this has a
a middle term of two this has a middle
term of -5 so it's going to be a little
bit more confusing to be able to create
this value C or is going to create the
perfect square trinomial but thankfully
for us there is a formula for us to be
able to identify c c is equal to B / 2
co^ s so what I'm simply going to do is
take the5 and you could even do positive
because it doesn't matter you're going
to square it 55s divid two Quin Square
well remember guys dividing by two is
the same thing as multiplying by 1/2 so
when I multiply by 1/2 on the top and
the bottom that's going to go to one I'm
going to be left with a -5 over 4^ 2ar
which is going to give me a 25 over 16
now this value is what we're going to
plug inside this parentheses so y = a -2
* x^2 - 5 X plus a 25 over 16 but here's
the little issue we can't just randomly
add a 25 over 16 onto the right side of
the equation right remember whatever you
do on one side you have to do on the
other side but at the beginning of the
video I told you I don't want to do
anything on this left hand side I want
to keep all my work on the right hand
side so to keep this equation still
equal if I add a 25 over 16 then I'm
going to have to subtract a 25 over 16
right as long as you add and subtract
the same value on the same side of the
equation you're still keeping the
equation equivalent but here's the thing
I actually didn't add a 25 or 16 because
remember the dist this is inside the
parentheses that's being multiplied byga
-2 that means everything inside here is
being multiplied by -2 so what I
actually added was a 25 over 16 * a -2
so when I subtract a 25 or 16 I also
need to multiply that by a -2 now what I
simply I'm going to look into doing is I
need to create this binomial squared all
right so how do we go about factoring
this to a binomial squared this was not
a problem a difficult problem to go and
Factor right X2 plus 2X plus one what
two numbers multi give you one add to
give you two X+ 1 * X+ 1 X+ One S but
what do you do when you have something
like fractions well thankfully there's
actually another easy way for us to be
able to do this all we simply need to
look into is our B / two once it's
simplified so our B / two is going to be
our value that's going to give that's
going to be in our binomial square if
your middle term is negative that means
your binomial is going negative so
therefore I have a x minus a 54 quantity
squ and then over here I just need to go
ahead and simplify this well a negative
* a negative is going to be a positive
and this again reduce to a 1 over 8 so
therefore now I'll have a positive 25
over 8 okay so now we've gone from
standard form all the way to vertex form
now we just need to go ahead and write
out our Transformations but for the sake
of this video I'm not going to write
them out but I will verbally say them
we're going to have a reflection about
the x-axis so instead of the graph
opening up it's going to be opening down
since my a is larger than one two is
larger than one I'm going to have a
vertical stretch as a factor of two it's
x - 54 remember the formula guys is X -
H that means H is equal to a 54 right
it's xus 54 so H equal to 54s that means
I'm going to shift the graphs 54s over
to the right and my K is going to be a
postive 25 over 8 so for K that means
I'm going to shift the graph up 25 over
8 units which looks like it's going to
be 3 * 8 so 3 and 1/8 would roughly be
there but there you go ladies and
gentlemen that is the process for
finding the uh Transformations I hope
that helped the student and I hope it's
going to help
you but
